In ''electronic systems'' a diagnostic board is a specialized device with diagnostic circuitry on a

printed circuit board A printed circuit board (PCB; also printed wiring board or PWB) is a medium used in Electrical engineering, electrical and electronic engineering to connect electronic components to one another in a controlled manner. It takes the form of a L ...

that connects to a computer or other electronic equipment replacing an existing module, or plugging into an expansion card slot. A multi-board electronic system such as a computer comprises multiple printed circuit boards or cards connected via

connector Connector may refer to: Hardware *Plumbing * Electrical connector, a device for joining electrical circuits together (sometimes known as ports, plugs, or interfaces) ** Gender of connectors and fasteners ** AC power plugs and sockets, devices tha ...

s. When a fault occurs in the system, it is sometimes possible to isolate or identify the fault by replacing one of the boards with a diagnostic board. A diagnostic board can range from extremely simple to extremely sophisticated. Simple standard diagnostic plug-in boards for computers are available that display numeric codes to assist in identifying issues detected during the

power-on self-test A power-on self-test (POST) is a process performed by firmware or software routines immediately after a computer or other digital electronic device is powered on. This article mainly deals with POSTs on personal computers, but many other embed ...

executed automatically during system startup.

Dummy board

A dummy board provides a minimal interface. This type of diagnostic board in intended to confirm that the interface is correctly implemented. For example, a PC

motherboard A motherboard (also called mainboard, main circuit board, mb, mboard, backplane board, base board, system board, logic board (only in Apple computers) or mobo) is the main printed circuit board (PCB) in general-purpose computers and other expand ...

manufacturer can test PCI functionality of a PC motherboard by connecting a dummy

PCI PCI may refer to: Business and economics * Payment card industry, businesses associated with debit, credit, and other payment cards ** Payment Card Industry Data Security Standard, a set of security requirements for credit card processors * Pro ...

board into each PCI slot on the motherboard

Extender board

An extender board (or ''board extender, card extender, extender card'') is a simple circuit board that interposes between a card cage

backplane A backplane (or "backplane system") is a group of electrical connectors in parallel with each other, so that each pin of each connector is linked to the same relative pin of all the other connectors, forming a computer bus. It is used as a backbo ...

and the circuit board of interest to physically 'extend' the circuit board of interest out from the card cage allowing access to both sides of the circuit board to connect diagnostic equipment such as an oscilloscope or systems analyzer. For example, a PCI extender board can be plugged into a PCI slot on a computer motherboard, and then a PCI card connected to the extender board to 'extend' the board into free space for access. This approach was common in the 1970s and 1980s particularly on

S-100 bus The S-100 bus or Altair bus, IEEE 696-1983 ''(withdrawn)'', is an early computer bus designed in 1974 as a part of the Altair 8800. The bus was the first industry standard expansion bus for the microcomputer industry. computers, consisting of ...

systems. The concept can become unworkable when signal timing is affected by the length of the signal paths on the diagnostic board, as well as introducing Radio Frequency Interference (RFI) into the circuit under test because of a lack of adequate shielding. The use of extender boards is declining because of the wider use of multilayer flexible circuit boards and overall cheaper components, particularly in the consumer end of the electronics market.

Sources

Vector Electronics & Technology
in

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Calif. is one of the few companies still making these legacy boards. Electronic engineering {{Electronics-stub